1. Field of the Invention
The present invention relates generally to surgical apparatus and, more particularly, to a suction ring apparatus which is fixable in position with respect to the human eye and which fixes the shape of the eye during surgical eye operations.
2. Description of the Prior Art
Rings of various constructions are used to stabilize the shape of the eye in eye operations. They can be sewn up, as in the case of Flieringa rings or they may be hollow rings whose cross-section is open towards the eye, of the kind used, for example, in refractive surgery (Barraquer rings). These latter rings are right-angled in cross-section, the open arms of the right angle engaging the eye and including between the same and the right-angle of the ring a space in which a negative pressure is produced. The negative pressure fixes the eye but increases the internal pressure therein. Rings of this kind cannot be used for eye operations in which the eye pressure must be maintained at normal pressures, i.e., in all eye-opening surgical techniques in which producing a negative pressure in the ring during the opening or cuttings of the eye would lead to the iris, lens and vitreous body advancing outwardly. These eye-opening operations are in particular those commonly practiced for cataract and perforating keratoplasties--i.e., the transfer of a corneal disc from a donor's eye to a patient's eye. An annular fixing of the eyeball which does not deform the eyeball and which does not increase pressure is desirable for all these eye-opening operations.
A suction ring comprising a right-angle section annular outer ring is described in pending U.S. patent application Ser. No. 462,052 filed Jan. 6, 1990 as a continuation of U.S. patent application Ser. No. 164,589, filed Mar. 7, 1988 and now abandoned, whose applicant is a joint inventor of the present invention. The annular outer ring of that application is formed with a bore which extends away from the ring axis and to which a hollow grip connectable to an external vacuum means can be connected; the outer ring carries an annular inner member which is engageable with the eye and which is substantially a right-angled triangle in cross-section.
It is an a object of the present invention to provide a suction ring apparatus for eye operations which enables the eye to be fixed reliably without deformation of the eyeball and without any increase in the internal pressure in the eye.
It is a further object of the present invention to provide a suction ring apparatus for eye operations which is non-movably disposed exactly in the limbus plane and does not contact the cornea.
It is a further object of the present invention to provide a suction ring apparatus for eye operations which ensures that a trepan (trephine) that is securable to the suction ring apparatus is always guided perpendicularly to the limbus plane and, therefore, always moves within the optical axis.
Still other objects and advantages will become apparent in light of the attached drawings and written description of the invention presented hereinbelow.